Homepage & Privacy/Terms Pages Restyle

We've redesigned the homepage and the privacy & terms pages.  Some of our goals were:

### Responsive Web

We included the "susy" compass gem to easily implement "magic responsive grids".  I've attached screenshots of how this works.  I'd love to discuss how this might be applicable in other areas of the app.

#### Homepage

![home - mobile](https://f.cloud.github.com/assets/3383/2057959/ea24f5ca-8b56-11e3-949b-82afa87f3d08.png)
![home - mobile tablet](https://f.cloud.github.com/assets/3383/2057960/ea2a45c0-8b56-11e3-9b1d-895824929d87.png)
![home - tablet](https://f.cloud.github.com/assets/3383/2057961/ea2aeade-8b56-11e3-93d4-fd1f2305cf8d.png)
![home - desktop](https://f.cloud.github.com/assets/3383/2057958/ea1c8b74-8b56-11e3-9ddc-ca7f0b009835.png)
![home - widescreen](https://f.cloud.github.com/assets/3383/2057962/ea2b98f8-8b56-11e3-845c-01bf620f3a13.png)

#### Privacy Page

![privacy - mobile](https://f.cloud.github.com/assets/3383/2057970/ff81678c-8b56-11e3-890c-63b8926409fc.png)
![privacy - tablet](https://f.cloud.github.com/assets/3383/2057971/ff81907c-8b56-11e3-9056-8b0c6aa1a48b.png)
![privacy - desktop](https://f.cloud.github.com/assets/3383/2057969/ff80eda2-8b56-11e3-96cd-5e519b41e119.png)
![privacy - widescreen](https://f.cloud.github.com/assets/3383/2057972/ff826b64-8b56-11e3-85cc-c3080bf1320e.png)

### Isolation

Make sure it's isolated so that our changes don't effect other sections of the site.  We did this by creating a new layout called "welcome".  We also namespace the new styles with "body.welcome" by adding a "welcome" class to the body.  Each page also gets specific action classes like "index", "privacy", or "terms".  I created a helper to assign the body classes for each page.

### Notes

* We haven't implemented the login page yet.  That's another pull request.
* We did have to update quite a few gems to get everything to work.  This is mostly because the ```Gemfile.lock``` was outdated and was not loading some of the new gems that we were including and so we were forced to delete the ```Gemfile.lock``` and ```bundle update```